Department of Physiology, School of Basic Medicine Sciences, Gannan Medical University, Ganzhou, P.R. China.
Pain Medicine Research Institute, Gannan Medical University, Ganzhou, P.R. China.
Acupunct Med. 2024 Oct;42(5):275-284. doi: 10.1177/09645284241279874. Epub 2024 Sep 27.
Neuropathic pain can be provoked by high mobility group box 1 (HMGB1) activation of toll-like receptor (TLR)4/nuclear factor (NF)-κB signaling in the dorsal root ganglion (DRG). Electroacupuncture (EA) has been reported to effectively alleviate neuropathic pain with few side effects, but its precise mechanism of action remains unknown. The aim of this study was to explore whether 2 Hz EA stimulation suppresses TLR4/NF-κB signaling in the DRG following spared nerve injury (SNI) in a rat model.
In this experiment, SNI rats were given 2 Hz EA once every other day for a total of 21 days. Paw withdrawal threshold (PWT) was measured to assess SNI-induced mechanical hypersensitivity, and western blotting and immunofluorescence staining were used to determine the levels of pain-related signaling molecules and pro-inflammatory mediators in the DRG.
SNI up-regulated HMGB1, TLR4, myeloid differentiation factor-88 adaptor protein (MyD88) and NF-κB p65 protein expression in the DRG. In addition, immunofluorescence staining demonstrated that SNI induced higher levels of TLR4 and MyD88 in the DRG. We also demonstrated co-localization of TLR4 and MyD88 with both calcitonin gene-related peptide (CGRP) and isolectin GS-IB4 in the DRG of SNI rats, respectively. Meanwhile, 2 Hz EA stimulation effectively reversed the elevations of HMGB1, TLR4, MyD88 and NF-κB p65 induced by SNI in the DRG, which was coupled with amelioration of SNI-induced mechanical hypersensitivity.
The results of this study suggested that inhibition of the TLR4/NF-κB signaling pathway in the DRG by 2 Hz EA might be exploited as a therapeutic option for neuropathic pain.
高迁移率族蛋白 B1（HMGB1）通过激活背根神经节（DRG）中的 Toll 样受体（TLR）4/核因子（NF）-κB 信号转导可引发神经性疼痛。电针（EA）已被报道可有效缓解神经性疼痛，且副作用较少，但确切的作用机制尚不清楚。本研究旨在探讨在 spared nerve injury（SNI）大鼠模型中，2 Hz EA 刺激是否通过抑制 TLR4/NF-κB 信号转导来缓解神经病理性疼痛。
在本实验中，SNI 大鼠每隔一天接受一次 2 Hz EA 刺激，共 21 天。通过测定机械缩足反射阈值（PWT）来评估 SNI 引起的机械性超敏反应，采用 Western blot 和免疫荧光染色法测定 DRG 中与疼痛相关的信号分子和促炎介质的水平。
SNI 上调了 DRG 中 HMGB1、TLR4、髓样分化因子 88 衔接蛋白（MyD88）和 NF-κB p65 蛋白的表达。此外，免疫荧光染色显示 SNI 诱导了 DRG 中 TLR4 和 MyD88 的表达增加。我们还发现 TLR4 和 MyD88 与降钙素基因相关肽（CGRP）和异硫氰酸荧光素 GS-IB4 在 SNI 大鼠 DRG 中均有共定位。同时，2 Hz EA 刺激有效逆转了 SNI 引起的 DRG 中 HMGB1、TLR4、MyD88 和 NF-κB p65 的升高，同时改善了 SNI 引起的机械性超敏反应。
本研究结果表明，2 Hz EA 抑制 DRG 中 TLR4/NF-κB 信号通路可能是治疗神经性疼痛的一种选择。
